We've had both. Our current is the power awning by Dometic. As stated previously the auto awning has very limited adjustment and like most mine has very little tilt. This also makes it more difficult to clean. I have to get on top of the RV to wash the top of the awning as you cant bring it down like you can on the manual awning.
A friend of mine recently had his motor go out and it was over $400 to replace it.
The only positive is the convenience of the push button in and out. That's nice when a storm is coming and you only have to hit the button to bring it in instead of fighting the wind and rain.
I like mine so far but fear the motor quitting while extended. I've read up on how to remove the allen bolt at the motor so it can be reeled in manually if that happens but it's really out of reach without a ladder.
If you do invest in an automatic it might be wise to get the one with the metal cover so it protects the fabric from the sun when its rolled in. That's the number one killer of the fabric is exposure to the elements.